MAC flapping when enabling vlan-bridge

From: C Chan (cch.ccie@gmail.com)
Date: Thu Mar 06 2008 - 20:34:41 ARST


Hi all experts,

Any idea how to resolve the MAC flapping problem when turning on
vlan-bridging in switch?
I am doing IEWB Lab 17 task 1.5. The following problem is occurred.
When I performed further check, I found the flapping MAC address is coming
from SW3 CPU.

What is the problem? and how to address it?

Topology: SW1 <-eth-chan-> SW2 <-eth-chan-> SW3 <-eth-chan-> SW4

BR,
CH

*SW2 error*
SW2#
5d13h: %SW_MATM-4-MACFLAP_NOTIF: Host 0012.01ef.ad92 in bridge group 1 is
flapping between port Vl8 and port Vl23
SW2#
5d13h: %SW_MATM-4-MACFLAP_NOTIF: Host 0012.01ef.ad92 in bridge group 1 is
flapping between port Vl23 and port Vl8
SW2#
5d13h: %SW_MATM-4-MACFLAP_NOTIF: Host 0012.01ef.ad92 in bridge group 1 is
flapping between port Vl8 and port Vl23
SW2#
5d13h: %SW_MATM-4-MACFLAP_NOTIF: Host 0012.01ef.ad92 in bridge group 1 is
flapping between port Vl23 and port Vl8

*SW3 check*
SW3#s mac-add | i 0012.01ef.ad92
 All 0012.01ef.ad92 STATIC CPU

*SW2# config*
bridge 1 protocol vlan-bridge
!
interface Vlan8
 ip address 173.1.8.8 255.255.255.0
 bridge-group 1
!
interface Vlan23
 ip address 173.1.23.8 255.255.255.0
 bridge-group 1
!



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